A plurality of anticollision and anti-obstacle devices for industrial trucks have been known from the state of the art, which decelerate the vehicle to a complete stop via mechanical, hydraulic, electrical, or electronic control means on impacting any type of obstacle, i.e., an object or a person, either by initiating a braking process, i.e., application of the brakes and/or by switching off the traveling mechanism. Such anti-obstacle devices are usually mounted in front of the front sides of the vehicles, especially in the direction of travel, as a consequence of which they are unable to move in a pushing unit, partly because they would mutually switch off one another due to contact of their protective devices, and partly because the necessary pushing forces cannot be transmitted.
DE-A 40 20 286 discloses an assembly line formed by automotive skids, in which the skids are moved up against each other without gaps after their own drives are automatically put out of operation, and continue to move as a pushing unit moved by a common, external drive module at adjustable speed in a restrictedly guided manner, for which the front and rear safety switching bails of each skid are pressed in, partially to a stop, via toggle levers when the skids run into each other. Since the pushing forces for moving on the entire pushing unit are transmitted directly via the toggle levers in this arrangement, these levers must be made as correspondingly robust levers in order to be able to absorb the pushing forces. The increase in weight caused by this also leads to an increase in the moment of inertia, and it may exert a delaying effect in the case of an emergency shutoff of the skid as a consequence of collision with an obstacle, because the sensitivity of the safety switching bail is reduced. Since these are usually equipped with elastic, readily compressible and deformable person protection devices in the form of so-called "bumpers," the transmission of pushing forces via the safety switching bails is defeated. Depending on the design and the surface cover of the safety switching bails, there also is a risk that they do not form a closed, walkable surface, thus increasing the risk of accident for the assembly workers, when they are pressed in only partially within the pushing unit.